The Western honeybee (Apis mellifera) belongs to the group of eusocial insects. The species is distributed globally and functions as important pollinator for plants. Especially the sophisticated and structured organization of the colony which can comprise tens of thousands of individuals is fascinating. Based on the age of individual bees, different tasks are performed in the hive (age-related polyethism). Young bees stay in the centre of the hive and work as nurse bees or build brood cells and honeycombs while increasing age leads bees more to the periphery, and finally the oldest bees leave the hive to forage for resources such as nectar and pollen. Honeybees show multiple well-developed traits and strategies that contribute to their success. The dance communication enables the bee colony to share information about promising food sites and ensure the efficient exploitation by fast recruitment of nestmates. With help of the bee’s sting and poison, a colony can collectively fight off enemies that might be much larger in size. Another interesting behaviour is active thermoregulation to create optimal temperatures in the bee hive. In periods of hot temperature, bees cool with water and wing air fanning, while cold temperatures are avoided by generating heat through trembling of the flight muscles. Due to this ability of heating up or cooling down, honeybees are distributed even across latitudes with longer periodes of cold temperatures and they are also established at higher elevations of mountain ranges.
This temperature adaptation is in the focus of my project. I investigate which genes might have an influence on thermoregulation of honeybees as an important ability for adaptation to high elevations. In collaboration with the University of Hohenheim and local African partners, bees will be collected from different elevations of African mountains (Mt. Kenya & Mt. Elgon in Kenya, Rwenzori Mountain system & Virunga mountain system in Uganda, Mt. Kilimanjaro & Mt. Meru in Tanzania). Then we will select candidate genes (e.g. octopamine receptors) with potential effects on adaptation to elevation, especially regarding thermoregulation. Gene expression levels in the bee brains are analysed via qRT-PCR. Several colonies will be translocated to other elevations together with the monitoring of colony fitness to get insights about local adaptation to elevation. Furthermore, I conduct feeding experiments with octopamine added to the diet of honeybee colonies to demonstrate the importance of octopamine signalling for heating of bees, and so the foraging onset. Flight activity of bees will be recorded with RFID chip technology. Besides, aggressiveness of colonies will be measured. Additionally, I will create bee knockout mutants by using the CRISPR/Cas9 method in the lab and test them for their cold resistance in behavioural assays.